Propagation of plants



Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE PROPAGATION OF PLANTSNo Drawing. Application March 17, 1937,

Serial No. 131,369

13 Claims.

This invention relates to the propagation of plants from cuttings, andhas for its object the provision of an improved method for inducingroot-growth on such cuttings. This application is a continuation in partof our copending application Serial No. 72,058, filed April 1, 1936.

It has heretofore been recognized that certain gases (e. g. ethylene)induce definite types of formative responses on plants, such asstimulation or retardation of the growth of certain tissues, and theinitiation of cell division which results in various kinds ofproliferations or in the formation of roots. As a result of anexhaustive investigation of the effects of various types of growthsubstances on plants, we have discovered that certain organic compoundsexercise a pronounced stimulating effect on root-growth, and are highlyvaluable in promoting and inducing root-growth on plant slips orcuttings. In this specification and'in the appended claims, the wordcutting and the expression cuttings and the like" are used genericallyto designate any part of a plant, including buds, sclons, and slips,used for purposes of propagation, and the invention advantageously maybe employed to promote plant propagation from any such plant part byinducing active callus formation, root-growth, and similar plantphysiological responses.

Among the organic compounds which we find useful for inducingroot-growth are naphthaleneacetic acid and its derivatives. In theappended claims these compounds are defined generically as naphthalenesubstitution products of a compound having the acetic acid structure asits nucleus, that is, the acetic acid structure (which does not includethe acid hydrogen atom oi acetic acid itself) is the base or foundationof the molecule of the compound. I

Based on the foregoing discovery, our present invention involves theimprovement in propagating plants from cuttings which comprises the stepof inducingroot-growth by subjecting the cutting to the action of asubstance of the group consisting of naphthaleneacetic acid and its de-5 rivatives.

acetic acid may be used in accordance with the invention, butalpha-naphthaleneacetic acid in general is preferred. Only a minuteamount of the substance is necessary to induce vigorous rootgrowth andhigh concentrations are usually in- Jurious rather than beneficial.

Naphthaleneaoetic acid itself is an especially satisfactory substancefor use in the practice of our invention, but derivativesof naphthalene-M acetic acid in general may be employed with Both alphaandbeta-naphthalene success. Among the derivatives of naphthaleneaceticacid which we have found of special advantage in the practice of theinvention are salts of naphthaleneacetlc acid and esters ofnaphthaleneacetic acid. The alkali metal salts (including the ammoniumsalt) and the alkali-earth metal salts of naphthaleneacetlc acid ingeneral are the preferred salts for use in carrying out the invention.The lower alcohol esters (such as the methyl and ethyl esters) ofnaphthaleneacetic acid constitute the preferred esters for use incarrying out the invention. So far as we have now determined, however,all of the salts and esters of naphthaleneacetic acid possess definitepowers of inducing root-growth and similar plant physiological responseson cuttings and the like. 1

Treatment of the more succulent type of plants, such as the tomato,African marigold, tobacco, etc., with the growth substances of thepresent invention (1. e. naphthaleneacetic acid and its derivatives) hasshown that roots may be induced to grow from any portion of the stern,and even from the leaves of many species. The growth substance may bemixed with lanolin, olive oil, paraflln oil, maize oil, castor oil,Amalie oil (a commercial mineral oil) and the like, and a thin film orthe mixture may be applied by rubbing with a glass rod on the epidermisof the region to be treated. The usual concentrations found mosteffective are from about 0.01 to 2% of the growth substance on theweight of lanolin or the like. Lanolin and similar preparations of thegrowth substance may be applied directly to the cutting, or they may beplaced on shoots which remain attached to the parent plant during theperiod of treatment and are then removed and made into cuttings that arehandled at this stage the same as is normally done in commercialpractice. when applied to the stems, the growth substances of thepresent invention definitely cause local initiation, of roots on growingplants 01' tomato, sun flower, marlgold, artichoke, buckwheat, dahlia,and' tobacco. If the plants are kept in a glass case after treatment,the new roots force their way through the epidermis and out into thehumid atmosphere. The time required for roots to make their appearancevaries with the growth substance used, the concentration, the species ofplants, and the exact place on the plant where the material is applied.

Naphthaleneacetic acid itself is especially eiiective for initiatingrootaon both stems and Thus,

0.01 to 2.0% solution in lanolin causes negative (away from side wheresubstance was applied) bending of tomato stems. Positive (toward sidewhere substance is applied) bending occurs when the concentration of thesubstance is high enough to injure the tissue or retard the normal rateof growth. A 0.1 to 2.0% solution of naphthaleneacetic acid in generalis optimum for inducing adventitious roots.

In general, it might be stated that the most effective concentration forroot initiation falls just below that causing positive bending of thestem, or at the point where there is slight retardation of growth. Whenthe concentration is high enough to cause evident injury, roots appearon the opposite side or adjoining the place on the stem where thesubstance is applied. This result indicates that as the growth substancediffuses away from the point of toxic concentration a range is reachedwhich is effective for inducing roots. Under favorable conditions, 5 tomg. of naphthaleneacetic acid per gram of lanolin causes roots to beinduced and appear through the epidermis on tomato in six days, marigoldin five days, tobacco in eight days, and artichoke in six days. Onemilligram of naphthaleneacetic acid per gram of lanolin is effective,but usually requires two days more to induce roots.

In commercial practice, treatment of the cutting or parent plant with awater solution of the growth substance is generally more satisfactoryand applicable than treatment with lanolin (and similar) preparations.Thus, the growth substance may be dissolved in the water (in which it isonly sparingly soluble), and the basal end of the plant cutting placedin the solution. The basal end of the cutting immersed in such asolution for from several hours to several days induces subsequentgrowth of excellent root systems. The concentration of the growthsubstance in the aqueous solution is relatively minute, say a fewmilligrams per 100 cc. of water. solutions containing 0.5 mg. to 10 mg.of naphthaleneacetic acid per 100 cc. of water give satisfactory resultsfor many species.

In practicing the invention with water solutions of the growthsubstances, the plant cutting is placed in the solution for a period oftime ranging from a few hours to several days. The cutting, aftertreatment in the solution, may be planted in a mixture of half sand andhalf peat moss, for example, or in soil. The effectiveness of thetreatment is indicated in many ways, such as the increased percentage ofrooted cuttings, increase in size of the root systems, earlierappearance of roots, greater total number of roots, and the emergence ofroots from stem tissue above the base of the cutting as well as at thebase.

Cuttings of American holly (Her opaca) placed in solutions ofnaphthaleneacetic acid (1 to 4 mg. per 100 cc.) for periods ranging fromeight hours to two days produced excellent root systems sixto ten weeksafter treatment and planting. These results are of special significancesince cuttings of American holly are dimcult to root. A similarfavorable response to treatment with watersolutions of naphthaleneaceticacid was obtained with Japanese maple at the end or six to ten weeks.Japanese holly (Hex crenata.) at the end or about four weeks, Tom at theend or eight to ten weeks. American elm at the end of four to six weeks,and with many other genera and species at the end of periods rangingtrom two to ten weeks.

As indicated above, alpha-naphthaleneacetlc acid, having the structuralformula and its derivatives are preferred as the growth substances ofthe invention and are considerably more effective in inducingroot-growth on cuttings and the like than beta-naphthaleneacetic acid,which'has the structural formula and its derivatives. The derivatives ofnaphthaleneacetic acid referred to herein and in the appended claims arethose compounds in which an atom other than a hydrogen atom or a radicalhas been substituted for the acid hydrogen atom of the naphthaleneaceticacid.

We claim:

1. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting thecutting to the action of a naphthalene substitution product of acompound having the acetic acid structure as its nucleus.

2. The improvement in propagating plants from cuttings and the likewhich comprises the step or inducing root-growth by subjecting the,cutting to the action of naphthaleneacetic acid.

3. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting thecutting to the action of an alkali metal salt of naphthaleneacetic acid.A

4. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting thecutting to the action of a lower alcohol ester of naphthaleneaceticacid.

5. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting the basalend of the cutting to the action of a substance of the group consistingof naphthaleneacetic acid, salts of naphthaleneacetlc acid, and estersof naphthaleneacetic acid.

6. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting the basalend of the cutting to the action of an alkali metal salt ofnaphthaleneacetic acid.

7. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting the basalend of the cutting to the action of an alkali metal salt. ofnaphthaleneacetic acid.

8. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by subjecting the basalend of the cutting to the action of a lower alcohol ester ofnaphthaleneacetic acid.

9. The improvement in propagating plants from cuttings and the likewhich comprises the step of inducing root-growth by immersion treatmentof the basal end of the cutting in an aqueous solution containingnaphthaleneacetic acid.

10. The improvement in? propagating plants from cuttings and the likewhich comprises the step 01' inducing root-growth by immersion treatmentof the basal end of the cutting in an aqueous solution containing analkali metal salt oi naphthaleneacetic acid.

11. The improvement in propagating plants from cuttings and the likewhich comprises the step 01' inducing root-growth by subjecting thebasal end of the cutting to the action of alphanaphthaleneacetic acid.

12. The improvement in propagating plants from cuttings and the likewhich comprises the CERTIFICATE OF CORRECTION.

Patent No 2,129, 600 .7

September 6, 1938 PEscYw. ZIMMERHAN, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 51 claim 2, for the word "or" read of; lines56and57, claim 6, strike out the words an alkali metal salt of; line 62,claim''(', after 'salt" strike out the period; and that the said LettersPatent should be read with this correction therein that the samemayconform to the record of the case in the Patent Office.

Signed and sealed this 25th day of October, A. D. 1938.

(Seal) Henry Van Aredale Acting Commissioner of Patents.

step 01' inducing root-growth by immersion treatment of the basal end ofthe cutting in an aqueous solution containing an alkali metal salt oinaphthaleneacetic acid.

11. The improvement in propagating plants from cuttings and the likewhich comprises the step 01' inducing root-growth by subjecting thebasal end of the cutting to the action of alphanaphthaleneacetic acid.

12. The improvement in propagating plants from cuttings and the likewhich comprises the CERTIFICATE OF CORRECTION.

Patent No 2,129, 600 .7

September 6, 1938 PEscYw. ZIMMERHAN, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 51 claim 2, for the word "or" read of; lines56and57, claim 6, strike out the words an alkali metal salt of; line 62,claim''(', after 'salt" strike out the period; and that the said LettersPatent should be read with this correction therein that the samemayconform to the record of the case in the Patent Office.

Signed and sealed this 25th day of October, A. D. 1938.

(Seal) Henry Van Aredale Acting Commissioner of Patents.

